The present invention relates to a coupling connector for attachment to and detachment from respirator devices which are shut off in the open circuit condition, and enabling the connection of the mask to a bottle of pressurised breathing gas.
The known connector devices comprise expansion means having one or two stages, and in the case of two-stage expansion means, the second is secured on the mask. This second stage is then integrated in a coupling connector which is either affixed on the snout of the mask or more commonly attachable to and detachable from the same.
In this last case, the fitting and removal may be performed, (for example by screwing (and unscrewing) or by insertion.
In the greater number of cases, the operation is arranged to occur under overpressure, to prevent penetration of toxic gas into the mask.
However, this operation under overpressure has two shortcomings:
At the instant in which the mask is placed in position on the face, the user either fits the mask and opens the bottle, which forces him to hold his breath for several seconds, which is not always an easy task, or he opens the bottle and places the mask over his face, which causes a loss of breathing gas for several seconds;
After the mask has been placed in position, it is impossible to check that it is gastight by shutting the mask intake by hand and by breathing in.
To eliminate these disadvantages, coupling devices have been devised which render it possible by a manual action to go through a stage of operation under vacuum initially, and then to change to the operating stage under overpressure.
This possibility is very risky and sometimes forbidden with full justification, since it does not provide any assurance against wrong handling causing the vacuum setting to be established whilst the user is present within the danger area.